RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value of Derivatives (Details) - CAD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value of Derivatives
Short-term portion of derivative assets	$ 623	$ 1,015
Current derivative liabilities	(738)	(898)
Total net financial asset/(liability)	(404)	(546)
Foreign exchange contracts
Fair Value of Derivatives
Total net financial asset/(liability)	(152)	(1,327)
Interest rate contracts
Fair Value of Derivatives
Total net financial asset/(liability)	(156)	910
Commodity contracts
Fair Value of Derivatives
Total net financial asset/(liability)	(96)	(139)
Other contracts
Fair Value of Derivatives
Total net financial asset/(liability)	0	10
Fair Value
Fair Value of Derivatives
Short-term portion of derivative assets	623	1,015
Long-term derivative assets	463	627
Current derivative liabilities	(738)	(898)
Long-term derivative liabilities	(752)	(1,290)
Total net financial asset/(liability)	(404)	(546)
Fair Value \| Foreign exchange contracts
Fair Value of Derivatives
Short-term portion of derivative assets	139	46
Long-term derivative assets	335	309
Current derivative liabilities	(128)	(566)
Long-term derivative liabilities	(498)	(1,116)
Total net financial asset/(liability)	(152)	(1,327)
Fair Value \| Interest rate contracts
Fair Value of Derivatives
Short-term portion of derivative assets	65	660
Long-term derivative assets	53	254
Current derivative liabilities	(186)
Long-term derivative liabilities	(88)	(4)
Total net financial asset/(liability)	(156)	910
Fair Value \| Commodity contracts
Fair Value of Derivatives
Short-term portion of derivative assets	418	302
Long-term derivative assets	75	61
Current derivative liabilities	(423)	(332)
Long-term derivative liabilities	(166)	(170)
Total net financial asset/(liability)	(96)	(139)
Fair Value \| Other contracts
Fair Value of Derivatives
Short-term portion of derivative assets	1	7
Long-term derivative assets		3
Current derivative liabilities	(1)
Total net financial asset/(liability)	0	10
Level 1 \| Fair Value
Fair Value of Derivatives
Short-term portion of derivative assets	142	65
Long-term derivative assets	0	0
Current derivative liabilities	(136)	(60)
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	6	5
Level 1 \| Fair Value \| Foreign exchange contracts
Fair Value of Derivatives
Short-term portion of derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0	0
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	0	0
Level 1 \| Fair Value \| Interest rate contracts
Fair Value of Derivatives
Short-term portion of derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	0	0
Level 1 \| Fair Value \| Commodity contracts
Fair Value of Derivatives
Short-term portion of derivative assets	142	65
Long-term derivative assets	0	0
Current derivative liabilities	(136)	(60)
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	6	5
Level 1 \| Fair Value \| Other contracts
Fair Value of Derivatives
Short-term portion of derivative assets	0	0
Long-term derivative assets		0
Current derivative liabilities	0
Total net financial asset/(liability)	0	0
Level 2 \| Fair Value
Fair Value of Derivatives
Short-term portion of derivative assets	308	803
Long-term derivative assets	412	583
Current derivative liabilities	(391)	(643)
Long-term derivative liabilities	(608)	(1,158)
Total net financial asset/(liability)	(279)	(415)
Level 2 \| Fair Value \| Foreign exchange contracts
Fair Value of Derivatives
Short-term portion of derivative assets	139	46
Long-term derivative assets	335	309
Current derivative liabilities	(128)	(566)
Long-term derivative liabilities	(498)	(1,116)
Total net financial asset/(liability)	(152)	(1,327)
Level 2 \| Fair Value \| Interest rate contracts
Fair Value of Derivatives
Short-term portion of derivative assets	65	660
Long-term derivative assets	53	254
Current derivative liabilities	(186)
Long-term derivative liabilities	(88)	(4)
Total net financial asset/(liability)	(156)	910
Level 2 \| Fair Value \| Commodity contracts
Fair Value of Derivatives
Short-term portion of derivative assets	103	90
Long-term derivative assets	24	17
Current derivative liabilities	(76)	(77)
Long-term derivative liabilities	(22)	(38)
Total net financial asset/(liability)	29	(8)
Level 2 \| Fair Value \| Other contracts
Fair Value of Derivatives
Short-term portion of derivative assets	1	7
Long-term derivative assets		3
Current derivative liabilities	(1)
Total net financial asset/(liability)	0	10
Level 3
Fair Value of Derivatives
Total net financial asset/(liability)	(131)
Level 3 \| Fair Value
Fair Value of Derivatives
Short-term portion of derivative assets	173	147
Long-term derivative assets	51	44
Current derivative liabilities	(211)	(195)
Long-term derivative liabilities	(144)	(132)
Total net financial asset/(liability)	(131)	(136)
Level 3 \| Fair Value \| Foreign exchange contracts
Fair Value of Derivatives
Short-term portion of derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0	0
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	0	0
Level 3 \| Fair Value \| Interest rate contracts
Fair Value of Derivatives
Short-term portion of derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	0	0
Level 3 \| Fair Value \| Commodity contracts
Fair Value of Derivatives
Short-term portion of derivative assets	173	147
Long-term derivative assets	51	44
Current derivative liabilities	(211)	(195)
Long-term derivative liabilities	(144)	(132)
Total net financial asset/(liability)	(131)	(136)
Level 3 \| Fair Value \| Other contracts
Fair Value of Derivatives
Short-term portion of derivative assets	0	0
Long-term derivative assets		0
Current derivative liabilities	0
Total net financial asset/(liability)	$ 0	$ 0

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483466/210-20-50-3

+ Details

Name:	us-gaap_DerivativeAssetsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-SubTopic 10
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480463/815-10-45-5

+ Details

Name:	us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

+ Details

Name:	us-gaap_DerivativeAssetsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

+ Details

Name:	us-gaap_DerivativeLiabilitiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

+ Details

Name:	us-gaap_DerivativeLiabilitiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-3

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_OtherContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: